My invention relates to an apparatus for continuously producing seals in tubular plastics film material. Apparatus is known comprising means for supplying the web of material, at least one heating beam travelling along with the web and subsequently returning, means for keeping the web mechanically tension-free at the location where it is warm, means for keeping the heated film layers one against the other up to a pressing station, said pressing station comprising two rollers at least one of which is provided with cooling means, and finally, means for discharging the web.
In this prior apparatus the heating beam is arranged on a drum, implying that one is limited to a fixed spacing between the seals produced in the tube. In case the sealing is intended to produce bags with the tube material it is thus only possible to obtain bags of a certain length.
In practice bags of a great variety of lengthwise dimensions is wanted for various purposes, which makes it thus necessary to have one apparatus available for each bag length required.
Further apparatus is known already which is capable of producing seals in a film web with various mutual distances. Here a continuously circulating belt carries a plurality of heating beam support units. These units are held up, whereby they slip with respect to the ongoing belt, in order to be freed at an appropriate moment. This apparatus is disadvantageous in that it results in a poor accuracy of the distances between the seals produced.